Interventional cardiology is expensive, sometimes dangerous, but ultimately reasonably effective at saving lives with 600,000 angioplasties per year in the US alone, at a cost of about $12 billion. With such widespread use, approaches that make this less invasive and less expensive would not only allow faster recovery, it could lower our ever-increasing national health care costs.
Viscous forces plays a dominant role at small length scales. Locomotion by microbots is hindered because familiar (macroscopic) swimming mechanisms are ineffective against these forces. In other words, movement at this micrometer length scale is akin to doing the backstroke in honey. Microorganisms overcome these limitations through physical adaptations, like rotating flagellum, that are difficult to artificially replicate and control.
Many interventional procedures in the cardiovascular system require invasive catheter-based methods (e.g. diagnostic angiography, angioplasty) to reach their intended targets. These systems are problematic because catheters cannot access the entire vascular system. Moreover, they are an inelegant approach to applications that require finesse, such as removing a blood clot without damaging the vessel wall. Because of the inherent advantages associated with a non-invasive approach for medical applications, magnetic field techniques have been used extensively to drive and direct microbots. These previous efforts are limited in their ability to control direction and continuously power the smaller devices.
U.S. Patent Publication No. 2006/0142632 to Meretei entitled “Systems and methods for removing plaque from a blood vessel” is incorporated by reference in its entirety. Meretei describes a system and method for removing accumulated plaque in a blood vessel using ferrofluids that are introduced to the bloodstream of a patent. The ferrofluids are magnetically manipulated and moved throughout the blood vessels of the patent with an external magnetic field generator to break up and remove accumulated plaque. U.S. Patent Publication No. 2009/0062828 to Marr entitled “Magnetic Field-Based Colloidal Atherectomy,” is incorporated by reference in its entirety. Marr describes methods, devices and systems for performing a non-invasive form of angioplasty using colloidal particles that can be magnetically controlled. Marr described the idea of rotating colloidal assemblies as biomedical microtools. Zhang, Li, et al. “Characterizing the swimming properties of artificial bacterial flagella” Nano Letters 9.10 (2009): 3663-3667, is incorporated by reference in its entirety. Zhang describes artificial bacterial flagella (ABF) consisting of helical tails similar to natural flagella comprising soft-magnetic heads. The ABFs are controlled wirelessly using a low rotating magnetic field. Ghosh, Ambarish, and Peer Fischer. “Controlled propulsion of artificial magnetic nanostructured propellers” Nano letters 9.6 (2009): 2243-2245 is incorporated by reference. Pak, On Shun, et al. “High-speed propulsion of flexible nanowire motors: Theory and experiments.” Soft Matter 7.18 (2011): 8169-8181, is incorporated by reference in its entirety. Pak describes a high-speed fuel-free magnetically-driven propeller for use in a biological environment.
Thus, there is a need for an improved mechanism and method to improve interventional procedures in biological systems. The present invention overcomes these and other issues.